1. Field of the Invention
The present invention relates to a recording apparatus for image recording by scanning with plural dots, such as a multi-beam laser printer or a multi-head ink jet printer.
2. Description of the Prior Art
In the field of recording apparatus for information recording on a recording medium, there is already known an image recording apparatus capable of forming plural dots in the subsidiary scanning direction in order to achieve high-speed recording. In such an image recording apparatus utilizing plural dots, it is also known to mount a semi-conductor laser array, used as the light source in the laser beam printer, or a multiple head, used in the ink jet printer, in an inclined position with respect to the subsidiary scanning direction, in order to increase the dot density in said subsidiary scanning direction. However, plural dots simultaneously formed by such inclined laser array or multiple head give inevitably give rise to phase differences between said dots along the main scanning direction, since such dots are not aligned in the subsidiary scanning direction.
In a conventional method for compensating the phase differences between such dots along the main scanning direction, a particular dot among said plural dots is detected at a determined position to generate a detection signal, which is utilized, with suitable delays, to form control signals for other dots. It has, however, been difficult, in such a method, to form control signals for other dots with exact timings.
In order to overcome this drawback the present applicant disclosed, in the U.S. patent application Ser. No. 164,522, a method of forming control signals for the dots by means of a high-frequency oscillating circuit, but such an oscillating circuit is very expensive and is a highly complicated in structure. Besides, though the error in each dot control signal can be reduced if a higher frequency is selected in the oscillating circuit, the selection of the frequency in practice has posed certain difficulties since it is to be determined in relation to other factors of the apparatus.